Blowers/007 Blowers Direct Drive Blowers by S4.pdf
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Index: Blowers
Subject: (7) Guidelines for Direct Drive Blowers Manufactured by Seasons-4
Date: October 24, 2013
Revised May 9, 2014
Revised February 17, 2017
Revised September 26, 2019
Seasons-4 will manufacture two types of direct drive plenum blowers: an open frame type, which will be referred to as Arr. 4 construction and an enclosed type, which will be referred to as a fan cell. Either type can be specified in a fan array, which indicates that multiple blowers are to be used, so Sales must specify arr. 4 or fan cell when they request a fan array. The blowers manufactured by Seasons-4 are selected based on the wheel manufacturer’s data, but they are NOT AMCA certified and cannot bear the AMCA seal since we are purchasing components only, and not the manufacturer’s tested assembly.
Wheel selections will be based on Greenheck APH or Twin City (TCF) EPFN (9-blade) for the arr. 4 blowers, with an option to go to TCF EPQN (12-blade) for sound considerations. Seasons-4 fan cell selections will be standardized on the TCF EPQN (12-blade) and will be selected using the TCF MPQN blower to account for the effect of the fan cell enclosure. Other available models include the Greenheck HPA and TCF MPLQN or MPLFN. These are considered “commercial-duty” fan cells (compared to the more industrial MPQN construction) and are available with compact housings for tighter spacing requirements. Other manufacturers may be considered for specific projects if required to meet project specifications. NOTE: Do not use Cook for direct drive plenum applications. Wheels are to be supplied from the fan manufacturer with a tapered hub and split tapered bushing (TCF is doing this currently for all Seasons-4 orders). Motor shaft size must be specified when ordering wheels.
The standard construction for the wheels will be mill finish aluminum and inlet cones will be steel with a powder coated gray finish. An optional powder coated white finish is also available. Inlet cones are also available in aluminum with a mill finish.
Inlet cones will have an option to be provided with piezometer ring for airflow measurement. Note that piezometer ring will not provide airflow measurement if one or more of the blowers is not running unless backdraft isolation dampers are provided for each blower to prevent re-circulation. Isolation dampers are optional and need to be specified at the time of design.
Motors for direct drive blowers will be rolled steel construction, with the exception of 3600 RPM motors which will be cast iron. Standard enclosure type will be ODP (or OPSB), with an option for TEFC. Please note that we may have to provide TEFC motors to get cast iron construction for 3600 RPM motors, even though TEFC may not be required by the project specification. Motors will be selected for nominal 1200, 1800 or 3600 RPM; 600 and 900 RPM motors should be avoided as these are costly and difficult to get. Motors can be under-driven or over-driven for selection. Motors can typically be over-driven up to 90 Hz. Note that if motor is under-driven, the actual motor HP will be less than the rated HP and this must be compensated for when selecting the motor. The Seasons-4 submittal program will perform this calculation and select the proper motor HP based on the RPM of the motor that was selected in the Seasons-4 blower program. If the motor is over-driven, there is some loss of torque and a safety factor has been added to the Seasons-4 blower program. If there is any concern on the motors selection on a direct drive application, please verify using the blower manufacturers program.
A single VFD to operate all blowers shall be standard. As an option, a redundant VFD or one VFD for each motor can be supplied. A VFD bypass should be avoided. If bypass is required on the VFD, the blower RPM should be selected near the synchronous speed of the motor to avoid a drastic change in airflow during operation in bypass.
Shaft grounding is standard for all direct drive blowers and will be purchased factory installed in the motors whenever possible. The standard method of shaft grounding will be the SGR shaft grounding rings by AEGIS.
Standard vibration isolation will be rubber-in-shear isolators, with options for unhoused or housed seismic isolators. At this time, fan cells are manufactured with only available with rubber-in-shear isolators. Fan cells that are internally isolated should be rigidly mounted to the floor and wall. No blower gasket is required for rigidly mounted fan cells.
Arr. 4 blower frames and fan cells will be air dry painted steel as standard. Optional finishes will be a two-part epoxy painted or powder coated. Fan cells will be standard without internal insulation. Standard fan cell insulation will be 2” rigid insulation with matte black facing (Permacote Linacoustic R-300) with a 3/16” perforated retainer. Rigid fiberglass with PSK white polymer facing and FSK foil facing options are also available. The perforated retainer will be unpainted galvanized, unless powder coated is specified.
Any project requiring vertical direct drive blowers manufactured by Seasons-4 will need to be assessed early in the process to insure that we do not have any manufacturing issues. We may elect to purchase these as full assemblies from the manufacturer.
